The present invention relates to an electronic digital pressure switch that detects a fluid pressure in a system for supplying or circulating a fluid, such as a gas or a liquid, and generates an output.
Hitherto, a refrigerator that forcibly circulates a refrigerant gas in a refrigerant circuit or a system, such as a gas forced-feed system for forcibly feeding a gas or the like uses a compressor for compressing and discharging a gas and also uses a digital pressure switch to control low/high pressures in the system (refer to, for example, Japanese Unexamined Patent Application Publication No. 2000-75810).
This type of a conventional digital pressure switch has a device for detecting the pressure of a gas in the system, a display unit for displaying the pressure detected by the detecting device, and a contact output that turns on/off according to the detected pressure. The contact output is used to, for example, stop a compressor if a refrigerant gas pressure on a low pressure side in a refrigerant circuit of a refrigerator comes down to a predetermined value.
Since the digital pressure switch is used for detecting gas pressures, as described above, a gas is drawn into the digital pressure switch itself. Hence, if the gas is flammable, there has been a danger in that leakage of the gas into the housing of the digital pressure switch causes the gas to accumulate therein and eventually explode.
A conventional digital pressure switch has been exclusively used for displaying pressure levels and controlling pressures in a system. If the digital pressure switch can be further used to carry out operation control of a unit in the system, such as the abovementioned compressor, and also to handle abnormal pressures, then the construction of the controller of the system can be simplified.